OnJava8-Examples/typeinfo/PetCount3.java
2015-12-15 11:47:04 -08:00

55 lines
1.7 KiB
Java

// typeinfo/PetCount3.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Using isInstance()
import typeinfo.pets.*;
import java.util.*;
import onjava.*;
public class PetCount3 {
static class Counter
extends LinkedHashMap<Class<? extends Pet>, Integer> {
public Counter() {
super(MapData.map(LiteralPetCreator.allTypes, 0));
}
public void count(Pet pet) {
// Class.isInstance() eliminates instanceofs:
for(Map.Entry<Class<? extends Pet>, Integer>
pair : entrySet())
if(pair.getKey().isInstance(pet))
put(pair.getKey(), pair.getValue() + 1);
}
@Override
public String toString() {
StringBuilder result = new StringBuilder("{");
for(Map.Entry<Class<? extends Pet>, Integer>
pair : entrySet()) {
result.append(pair.getKey().getSimpleName());
result.append("=");
result.append(pair.getValue());
result.append(", ");
}
result.delete(result.length() - 2, result.length());
result.append("}");
return result.toString();
}
}
public static void main(String[] args) {
Counter petCount = new Counter();
Pets.stream()
.limit(20)
.peek(petCount::count)
.forEach(p -> System.out.print(
p.getClass().getSimpleName() + " "));
System.out.println("\n" + petCount);
}
}
/* Output:
Rat Manx Cymric Mutt Pug Cymric Pug Manx Cymric Rat
EgyptianMau Hamster EgyptianMau Mutt Mutt Cymric Mouse Pug
Mouse Cymric
{Pet=20, Dog=6, Cat=9, Rodent=5, Mutt=3, Pug=3,
EgyptianMau=2, Manx=7, Cymric=5, Rat=2, Mouse=2, Hamster=1}
*/